Skip to main content

Full text of "The Cambridge Natural History"

See other formats

44-8                                   TEETH OF SEALS                                   CHAP.

six, and the additional molar was at the end of the series, thus
suggesting a lengthening of jaw coupled with an increase in
number of teeth.

The incisor teeth of the Pinnipedia differ from those of the
land Garnivora in that there are nearly always fewer than -§-, at
least in the adult animal. In possessing lobulated kidneys the
Pinnipedia differ from all terrestrial Carnivores except the Otters
and Bears—a significant fact.

In the characters of the skeleton, the Pinnipedia show many
peculiarities. The cranial part of the skull is proportionately
to the facial part greater than in terrestrial Carnivora; there is
no lachrymal hone, and the orbit is to some extent defective in
ossification. The alisphenoid canal, so important a feature in
the Carnivora, may be present or absent. It is present, for
example, in Otaria jubata,? This genus also has the more

Fia. 228. — Patagonian Sea-Lion.     Otairia jubata.    x

primitive small and rugged tympanic hnllae, which are inflated
and more Cat-like in others. The vertebrae show an interesting
Creodont peculiarity in the complex interlocking arrangements of
the zygapophyses of the dorsal vertebrae. The ossicula auditus
differ from those of their terrestrial allies in their large size and
massive growth. In this they have come to be like those of the
Whales and Sirenians.
There  is  no   doubt   about   their  close  resemblance   to   the
1 Muiie. Trans. ZooL ffae. xm